diff -r 156985f2dec0 -r 41d3e307a7c1 mercurial/scmutil.py
--- a/mercurial/scmutil.py	Sun Nov 22 21:40:23 2015 -0800
+++ b/mercurial/scmutil.py	Mon Nov 02 17:33:18 2015 +0000
@@ -1176,7 +1176,7 @@
     """
     # experimental config: format.generaldelta
     return (ui.configbool('format', 'generaldelta', False)
-            or ui.configbool('format', 'usegeneraldelta', False))
+            or ui.configbool('format', 'usegeneraldelta', True))
 
 def gddeltaconfig(ui):
     """helper function to know if incoming delta should be optimised